The social functioning in dementia scale (SF-DEM): Exploratory factor analysis and psychometric properties in mild, moderate, and severe dementia.

Introduction: The psychometric properties of the social functioning in dementia scale over different dementia severities are unknown.

Methods: We interviewed 299 family carers of people with mild, moderate, or severe dementia from two UK research sites; examined acceptability (completion rates); conducted exploratory factor analysis; and tested each factor's internal consistency and construct validity.

Results: Of 299, 285 (95.3%) carers completed questionnaires. Factor analysis indicated three distinct factors with acceptable internal consistency: spending time with other people , correlating with overall social function (r = 0.56, P  < .001) and activities of daily living (r = -0.48, P  < .001); communicating with other people correlating with activities of daily living (r = -0.66, P  < .001); and sensitivity to other people correlating with quality of life (r = 0.35, P  < .001) and inversely with neuropsychiatric symptoms (r = -0.45, P  < .001). The three factors' correlations with other domains were similar across all dementia severities.

Discussion: The social functioning in dementia scale carer version measures three social functioning domains and has satisfactory psychometric properties in all severities of dementia.